I have a carton of eggs without a best-before date on it. I think I have had the eggs for about two or three weeks. Is there any way to tell if they are fresh?--Lin
There are two ways to tell how fresh your eggs are, but you need to remember that these are rough guidelines and that they don't necessarily tell you if the eggs are safe to eat.
The first method is to fill a container with cold water. If your egg is fairly fresh, it will sink to the bottom of the bowl and lay on its side, maybe tilted a little toward the rounder end up. As the egg gets older, it loses moisture and the air sac inside the rounder end enlarges. A somewhat older egg may still sink to the bottom of the bowl, but will rest on the pointy end. If the egg floats with the round end slightly above water, then it is old and should be discarded.
The container needs to be deep enough that you can clearly see if the egg is submerged, touching the bottom, or floating. A four cup (one liter) glass measuring cup is ideal for this test.
If you were planning to crack the egg anyway, you can also tell the freshness by emptying the egg onto a flat dish, such as a side plate. If the egg is completely fresh, the white will stay together and mound up noticeably around the yolk so that it clearly can be seen to have two levels. The yolk will be rounded and well domed. As the egg get older, the white becomes more runny, spreads more on the plate and doesn't rise around the yolk. The yolk also becomes flatter. If the white is watery and shows little or no rise in level around the yolk, then the egg is quite old.
As I said above though, these are tests only of the age of an egg and don't tell you about the safety. improperly stored eggs can be contaminated and still pass these tests. For safety, always try to be sure and buy eggs in a carton with a clear date, keep them in the carton, and don't move eggs from one partly used carton into another. Always use eggs before the best-before date.